Transition metal deposition method

ABSTRACT

Methods of depositing transition metal on a substrate. The disclosure further relates to a transition metal layer, to a structure and to a device comprising a transition metal layer. In the method, transition metal is deposited on a substrate by a cyclical deposition process, and the method comprises providing a substrate in a reaction chamber, providing a transition metal precursor to the reaction chamber in a vapor phase and providing a reactant to the reaction chamber in a vapor phase to form transition metal on the substrate. The transition metal precursor comprises a transition metal from any of groups 4 to 6, and the reactant comprises a group 14 element selected from Si, Ge or Sn.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationSer. No. 63/129,024 filed Dec. 22, 2020 titled TRANSITION METALDEPOSITION METHOD, the disclosure of which is hereby incorporated byreference in its entirety.

FIELD

The present disclosure relates to methods and apparatuses for themanufacture of semiconductor devices. More particularly, the disclosurerelates to methods and systems for depositing transition metal on asubstrate, and layers comprising transition metal.

BACKGROUND

Semiconductor device fabrication processes generally use advanceddeposition methods for forming metal and metal-containing layers withspecific properties. Transition metals in groups 4 (titanium, zirconium,hafnium), 5 (vanadium, niobium, tantalum) and 6 (chromium, molybdenumand tungsten) may have many of the advantages sought in the art. Forexample, they may be useful as a conductor material in back end of line(BEOL) or mid end of line (MEOL) applications, or in buried power railor in work function layer in logic applications and in word or bit linein advanced memory applications. Additionally, they may be used in metalgate applications.

The deposition of high quality metallic thin films by atomic layerdeposition remains challenging, especially for electropositive elements,and for metals that readily form nitride or carbide phases.Electropositive elements are difficult to reduce to the elemental form,often requiring powerful reducing agents, unusual conditions, orplasma-based approaches. Some metallic elements, especially those fromgroups 4, 5, and 6, often incorporate carbon or nitrogen from either themetal precursor ligands or from the co-reactants used in deposition togenerate a metal carbide or metal nitride. Avoiding ligands andco-reactants containing carbon and nitrogen is difficult, and severelylimits the selection of possible chemistry. Thus there is need in theart for alternative or improved methods for depositing transition metalsor transition metal-containing layers.

Any discussion, including discussion of problems and solutions, setforth in this section has been included in this disclosure solely forthe purpose of providing a context for the present disclosure. Suchdiscussion should not be taken as an admission that any or all of theinformation was known at the time the invention was made or otherwiseconstitutes prior art.

SUMMARY

This summary may introduce a selection of concepts in a simplified form,which may be described in further detail below. This summary is notintended to necessarily identify key features or essential features ofthe claimed subject matter, nor is it intended to be used to limit thescope of the claimed subject matter.

Various embodiments of the present disclosure relate to methods ofdepositing transition metal.

In the current disclosure, methods of depositing transition metal on asubstrate by a cyclical deposition process are disclosed. The methodscomprise providing a substrate in a reaction chamber, providing atransition metal precursor to the reaction chamber in a vapor phase andproviding a reactant to the reaction chamber in a vapor phase to formtransition metal on the substrate. The transition metal precursoraccording to the current disclosure comprises a transition metal fromany of groups 4 to 6, and the reactant comprises a group 14 elementselected from Si, Ge or Sn.

The current disclosure further relates to a transition metal layerproduced by the method according to the current disclosure. Thus, asubstrate is provided in a reaction chamber, a transition metalprecursor comprising a transition metal from any of groups 4 to 6 isprovided the reaction chamber in a vapor phase, and a reactantcomprising a group 14 element selected from Si, Ge or Sn is provided tothe reaction chamber to form transition metal on the substrate.

In an additional aspect, the current disclosure relates to a structurecomprising transition metal deposited by a method according to thecurrent disclosure. The transition metal comprised in the structure maybe deposited as a layer. In other words, it may be a transition metallayer. As used herein, a “structure” can be or include a substrate asdescribed herein. Structures can include one or more layers overlyingthe substrate, such as one or more layers formed by a method accordingto the current disclosure. The structure may be, for example, a via or aline in BEOL, or a contact or a local interconnect in MEOL. Thestructure may also be a work function layer in a gate electrode, or aburied power rail in logic applications, as well as a word line or a bitline in an advanced memory application.

In yet another aspect, the current disclosure relates to a semiconductordevice comprising transition metal deposited by a method according tothe current disclosure. The device may be, for example, a gateelectrode, a logic or a memory device.

In a further aspect, a deposition assembly is disclosed. The depositionassembly is constructed and arranged to deposit transition metal on asubstrate. The deposition assembly for depositing transition metal on asubstrate according to the current disclosure comprises one or morereaction chambers constructed and arranged to hold the substrate, and aprecursor injector system constructed and arranged to provide atransition metal precursor and/or a reactant into the reaction chamberin a vapor phase. The deposition assembly further comprises a precursorvessel constructed and arranged to contain a transition metal precursorcomprising a transition metal from any of groups 4 to 6 and a reactantvessel constructed and arranged to contain a reactant comprising a group14 element selected from Si, Ge or Sn. The deposition assembly isconstructed and arranged to provide the transition metal precursorand/or the reactant via the precursor injector system to the reactionchamber to deposit transition metal on the substrate. In an assemblyaccording to the current disclosure, a transition metal precursor and/ora reactant may be evaporated with a direct liquid injector. In suchembodiments, then precursor and or reactant liquid is pumped from thevessel and directly injected in a flow of carrier gas.

The following abbreviations shall be used throughout this disclosure: Mestands for methyl (CH₃) and Et for ethyl (C₂H₅). nPr or Pr stands forn-propyl, iPr for isopropyl, nBu or Bu for n-butyl, tBu for tert-butyl,sBu for sec-butyl, nPn or Pn for n-pentyl and tPn for tert-pentyl. Bzstands for bezene and Cp for cyclopentadienyl,

In this disclosure, any two numbers of a variable can constitute aworkable range of the variable, and any ranges indicated may include orexclude the endpoints. Additionally, any values of variables indicated(regardless of whether they are indicated with “about” or not) may referto precise values or approximate values and include equivalents, and mayrefer to average, median, representative, majority, or the like.Further, in this disclosure, the terms “including,” “constituted by” and“having” refer independently to “typically or broadly comprising,”“comprising,” “consisting essentially of,” or “consisting of” in someembodiments. In this disclosure, any defined meanings do not necessarilyexclude ordinary and customary meanings in some embodiments.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosure and constitute a part of thisspecification, illustrate exemplary embodiments, and together with thedescription help to explain the principles of the disclosure. In thedrawings

FIGS. 1A and 1B illustrate two exemplary embodiments of a methodaccording to the current disclosure.

FIG. 2 depicts an exemplary structure comprising a transition metallayer according to the current disclosure.

FIG. 3 presents a deposition apparatus according to the currentdisclosure in a schematic manner.

FIG. 4 depicts an exemplary device comprising transition metal depositedaccording to the current disclosure.

FIG. 5 , panels A to D depicts devices comprising transition metaldeposited according to the current disclosure.

FIG. 6 is a representation of a buried power rail comprising transitionmetal deposited according to the current disclosure.

FIG. 7 depicts a device comprising a work function layer comprisingtransition metal deposited according to the current disclosure.

FIG. 8 illustrates word lines in a 3D NAND comprising transition metaldeposited according to the current disclosure.

FIG. 9 displays an exemplary embodiment of word lines in a DRAMcomprising transition metal deposited according to the currentdisclosure.

DETAILED DESCRIPTION

The description of exemplary embodiments of methods, structures, devicesand apparatuses provided below is merely exemplary and is intended forpurposes of illustration only. The following description is not intendedto limit the scope of the disclosure or the claims. Moreover, recitationof multiple embodiments having indicated features is not intended toexclude other embodiments having additional features or otherembodiments incorporating different combinations of the stated features.For example, various embodiments are set forth as exemplary embodimentsand may be recited in the dependent claims. Unless otherwise noted, theexemplary embodiments or components thereof may be combined or may beapplied separate from each other.

The current disclosure relates to a method of depositing transitionmetal on a substrate. The method comprises providing a substrate in areaction chamber, providing a transition metal precursor in the reactionchamber in vapor phase and providing a reactant to the reaction chamberin a vapor phase to form transition metal on the substrate. In thecurrent disclosure, transition metal may be deposited predominantly, orin some embodiments substantially completely or completely, as anelemental metal. By elemental, transition metal is herein meanttransition metal with an oxidation state of zero. A transition metaldeposited according to the current disclosure may have partly anoxidation state of 0, +2, +3, +4, +5 and/or +6. In some embodiments, atleast 60% of transition metal is deposited as elemental metal. In someembodiments, at least 80% or at least 90% of transition metal isdeposited as elemental metal. In some embodiments, at least 93% or 95%of transition metal is deposited as elemental metal.

Transition Metal Precursor

The terms “precursor” and “reactant” can refer to molecules (compoundsor molecules comprising a single element) that participate in a chemicalreaction that produces another compound. A precursor typically containsportions that are at least partly incorporated into the compound orelement resulting from the chemical reaction in question. Such aresulting compound or element may be deposited on a substrate. Areactant may me an element or a compound that is not incorporated intothe resulting compound or element to a significant extent. However, areactant may also contribute to the resulting compound or element incertain embodiments.

As used herein, “a transition metal precursor” includes a gas or amaterial that can become gaseous and that can be represented by achemical formula that includes transition metal selected from groups 4(titanium, zirconium, hafnium), 5 (vanadium, niobium, tantalum) or 6(chromium, molybdenum and tungsten) of the periodic table of elements.

In some embodiments, the transition metal precursor comprises a group 4transition metal. The transition metal precursor may thus comprisetitanium (Ti). The transition metal precursor may alternatively comprisezirconium (Zr). As another alternative, the transition metal precursormay comprise hafnium (Hf). In some embodiments, the transition metal inthe transition metal precursor is selected from a group consisting oftitanium, zirconium and hafnium. In some embodiments, the transitionmetal in the transition metal precursor is selected from a groupconsisting of titanium and hafnium.

In some embodiments, the transition metal precursor comprises a group 5transition metal. The transition metal precursor may thus comprisevanadium (V), or the transition metal precursor may comprise niobium(Nb), or the transition metal precursor may comprise tantalum (Ta). Insome embodiments, the transition metal in the transition metal precursoris selected from a group consisting of vanadium, niobium and tantalum.In some embodiments, the transition metal in the transition metalprecursor is selected from a group consisting of vanadium and tantalum.

In some embodiments, the transition metal precursor comprises a group 6transition metal. The transition metal precursor may comprise chromium(Cr). Alternatively, the transition metal precursor may comprisemolybdenum (Mo). The transition metal precursor may comprise tungsten(W). In some embodiments, the transition metal in the transition metalprecursor is selected from a group consisting of chromium, molybdenumand tungsten. In some embodiments, the transition metal in thetransition metal precursor is selected from a group consisting ofmolybdenum and tungsten.

In some embodiments, transition metal precursor is provided in a mixtureof two or more compounds. In a mixture, the other compounds in additionto the transition metal precursor may be inert compounds or elements. Insome embodiments, transition metal precursor is provided in acomposition. Compositions suitable for use as composition can include atransition metal compound and an effective amount of one or morestabilizing agents. Composition may be a solution or a gas in standardconditions.

In some embodiments, transition metal precursor comprises a transitionmetal atom and an organic ligand. In some embodiments, transition metalprecursor comprises a metal-organic precursor comprising a transitionmetal according to the current disclosure. Thus, the transition metalprecursor is a metal-organic precursor. By a metal-organic precursor isherein meant a transition metal precursor comprising a metal, such as agroup 4-6 transition metal according to the current disclosure, and anorganic ligand, wherein a metal atom is not directly bonded to a carbonatom. In some embodiments, a metal-organic precursor comprises onetransition metal atom, which is not directly bonded with a carbon atom.In some embodiments, a metal-organic precursor comprises two or moretransition metal atoms, none of which is directly bonded to a carbonatom. In some embodiments, a metal-organic precursor comprises two ormore transition metal atoms, wherein at least one transition metal atomis not directly bonded to a carbon atom.

In some embodiments, transition metal precursor comprises anorganometallic compound comprising a transition metal according to thecurrent disclosure. Thus, the transition metal precursor is anorganometallic precursor. By an organometallic precursor is herein meanta transition metal precursor comprising a transition metal, such as agroup 4-6 transition metal according to the current disclosure, and anorganic ligand, wherein the transition metal atom is directly bonded toa carbon atom. In embodiments in which an organometallic precursorcomprises two or more transition metal atoms, all of the metal atoms aredirectly bonded with a carbon atom.

In some embodiments, the transition metal precursor comprises only atransition metal atom according to the current disclosure, carbon andhydrogen. In other words, transition metal precursor does not containoxygen, nitrogen or other additional elements. However, in someembodiments, the metal-organic or organometallic precursor comprises atransition metal according to the current disclosure, carbon, hydrogenand at least one additional element. The additional element may be, forexample, oxygen, nitrogen or a halogen. In some embodiments, theadditional element is not directly bonded to the metal. Thus, in someembodiments, a transition metal precursor does not contain ametal-nitrogen bond. In some embodiments, a transition metal precursordoes not contain a metal-oxygen bond. In some embodiments, a transitionmetal precursor does not contain a metal-halogen bond. The at least oneadditional element in a metal-organic or organometallic precursor may bea ligand. The at least one additional element may thus be an additionalligand. In some embodiments, the metal-organic or organometallicprecursor comprises an additional ligand, and the ligand is a halide. Insome embodiments, the metal-organic or organometallic precursor maycomprise at least two additional ligands, and one or two of theadditional ligands may be a halide. Each of the additional ligands maybe independently selected. A halide may be selected from the groupconsisting of chloro, bromo and iodo. Thus a ligand may be a halogenatom, selected from the group consisting of chlorine, bromine andiodine.

In some embodiments, transition metal precursor comprises at least twoorganic ligands. In some embodiments, transition metal precursorcomprises at least three organic ligands. In some embodiments,transition metal precursor comprises four organic ligands. In someembodiments, transition metal precursor comprises a organic ligand and ahydride ligand. In some embodiments, transition metal precursorcomprises a organic ligand and two or more hydride ligands. In someembodiments, transition metal precursor comprises two organic ligandsand two hydride ligands. In some embodiments, one or more of the organicligands is a hydrocarbon ligand.

In some embodiments, transition metal precursor comprises cyclicportions. For example, the transition metal precursor may comprise abenzene or a cyclopentadienyl ring. The transition metal precursor maycomprise one or more benzene rings. In some embodiments, the transitionmetal precursor comprises two benzene rings. One or both benzene ringsmay comprise hydrocarbon substituents. In some embodiments, each benzenering of the transition metal precursor comprises an alkyl substituent.An alkyl substituent may be a methyl group, an ethyl group, or a linearor branched alkyl group comprising three, four, five or six carbonatoms. For example, the alkyl substituent of the benzene ring (Bz) maybe an n-propyl group or an iso-propyl group. Further, the alkylsubstituent may be an n-, iso-, tert- or sec-form of a butyl, pentyl orhexyl moiety. In some embodiments, the transition metal precursorcomprises, consist essentially of, or consist ofbis(ethylbenzene)transition metal. In some embodiments, a transitionmetal precursor comprises, consist essentially of, or consist of,V(Bz)₂, MoBz₂, CrBz₂, WBz₂, V(EtBz)₂, Mo(EtBz)₂, Cr(EtBz)₂, or W(EtBz)₂.

The transition metal precursor may comprise one or more cyclopentadienylgroups. In some embodiments, the transition metal precursor comprisestwo cyclopentadienyl groups. A cyclopentadienyl group may be similarlysubstituted as a benzene group. In other words, one or more of thecyclopentadienyl groups may comprise hydrocarbon substituents. In someembodiments, one or both of the cyclopentadienyl groups has an alkylsubstituent, such as a methyl group, an ethyl group, or a linear orbranched alkyl group comprising three, four, five or six carbon atoms.For example, the alkyl substituent of the cyclopentadienyl group may bean n-propyl group, an iso-propyl group. Further, the alkyl substituentmay be an n-, iso-, tert- or sec-form of a butyl, pentyl or hexylmoiety.

Some examples of transition metal precursors according to the currentdisclosure comprising a cyclopentadienyl moiety are TiCp₂Cl₂, TiCp₂Br₂,TiCp₂, TiCp₂(CO)₂, TiCp₂I₂, TiCp₂H₂, TiCpCl₃, TiCpBr₃, TiCpI₃, HfCp₂Cl₂,HfCp₂Br₂, HfCp₂, HfCp₂(CO)₂, HfCp₂I₂, HfCp₂H₂, HfCpCl₃, HfCpBr₃, HfCpI₃,ZrCp₂Cl₂, ZrCp₂Br₂, ZrCp₂, ZrCp₂(CO)₂, ZrCp₂I₂, ZrCp₂H₂, ZrCpCl₃,ZrCpBr₃, ZrCpI₃, VCp₂Cl₂, VCp₂Br₂, VCp₂I₂, VCp₂, VCp₂(CO)₄, TaCp₂Cl₂,TaCp₂I₂, TaCp₂Br₂, TaCp₂H₂, NbCp₂, NbCp₂H₂, NbCp₂Cl₂, MoCp₂Cl₂, MoCp₂H₂,CrCp₂H₂, CrCp₂, CrCp₂Cl₂, WCp₂H₂, WCp₂Cl₂, WCp₂Br₂ and WCp₂I₂.

Some further examples of cyclopentadienyl-containing transition metalprecursors are Ti(iPrCp)₂Cl₂, Ti(iPrCp)₂, Ti(MeCp)₂Cl₂, Ti(MeCp)₂,Ti(EtCp)₂Cl₂, Ti(EtCp)₂, Hf(iPrCp)₂Cl₂, Hf(iPrCp)₂, Hf(MeCp)₂Cl₂,Hf(MeCp)₂, Hf(EtCp)₂Cl₂, Hf(EtCp)₂, Zr(iPrCp)₂Cl₂, Zr(iPrCp)₂,Zr(MeCp)₂Cl₂, Zr(MeCp)₂, Zr(EtCp)₂Cl₂, Zr(EtCp)₂, V(iPrCp)₂Cl₂,V(iPrCp)₂, V(MeCp)₂Cl₂, V(MeCp)₂, V(EtCp)₂Cl₂, V(EtCp)₂, Mo(iPrCp)₂Cl₂,Mo(iPrCp)₂H₂, Mo(EtCp)₂H₂, Cr(MeCp)₂, Cr(EtCp)₂, Cr(iPrCp)₂, Cr(tBuCp)₂,Cr(nBuCp)₂, Cr(Me₅Cp)₂, Cr(Me₄Cp)₂, W(EtCp)₂H₂, W(iPrCp)₂Cl₂ andW(iPrCp)₂H₂.

In some embodiments, the transition metal precursor may comprise acarbonyl group-containing ligand. For example, the transition metalprecursor may comprise, consist essentially of, or consist of Mo(CO)₆,Mo(1,3,5-cycloheptatriene)(CO)₃. Additionally, in some embodiments, thetransition metal precursor comprises a nitrosyl group-containing ligand.For example, the molybdenum precursor may comprise, consist essentiallyof, or consist of MoCp(CO)₂(NO).

Reactant

In a method according to the current disclosure, reactant comprises agroup 14 element selected from silicon (Si), germanium (Ge) or tin (Sn).In some embodiments, the reactant comprises a group 14 element selectedfrom a group consisting of Si and Ge. In some embodiments, the reactantcomprises a group 14 element selected from a group consisting of Si andSn. In some embodiments, the reactant comprises a group 14 elementselected from a group consisting of Ge and Sn.

In some embodiments, a reactant comprises one atom of a group 14 elementaccording to the current disclosure. In some embodiments, a reactantcomprises two atoms of a group 14 element according to the currentdisclosure. The two or more atoms of group 14 element may be the same ora different element. For example, the reactant may contain two Si atoms,two Ge atoms or two Sn atoms. Alternatively, the reactant may comprise aSi atom and a Ge atom, a Si atom and a Sn atom or a Sn atom and a Geatom. In some embodiments, a reactant comprises two atoms of a group 14element according to the current disclosure bonded to each other.

In some embodiments, a reactant comprises two atoms of a group 14element according to the current disclosure bonded to each other, andeach atom of the group 14 element has a halogen atom attached to it. Thehalogen may be, for example, Cl, F or I. In some embodiments, a reactantcomprises two atoms of a group 14 element according to the currentdisclosure bonded to each other, and each atom of the group 14 elementhas a an alkyl group attached to it. For example, the alkyl group may bea methyl, ethyl, propyl, butyl or pentyl.

In some embodiments, a reactant comprises a Si—Si bond. In someembodiments, a reactant comprises a Ge—Ge bond. In some embodiments, areactant comprises a Sn—Sn bond. In some embodiments, a reactantcomprises a Si—Si bond with a halogen atom attached to each Si atom. Insome embodiments, a reactant comprises a Ge—Ge bond with a halogen atomattached to each Ge atom. In some embodiments, a reactant comprises aSn—Sn bond with a halogen atom attached to each Ge atom.

The reactant may comprise an organic group. An organic group is a groupcontaining a carbon-hydrogen bond. Thus, the reactant comprises a group14 element selected from a group consisting of Si, Ge and Sn, and anorganic group. The reactant may comprise a hydrocarbon containing atleast one carbon atom. There may be one, two, three or four organicgroups in a reactant. Each organic group may independently contain 1 to12 carbon atoms. For example, each organic group may independentlycomprise a C1 to C4 group (i.e. contain from one to four carbon atoms),a C1 to C6 group, a C1 to C8 group, a C1-C10 group, a C2 to C12 group, aC2 to C6 group, a C2 to C6 group, or a C4 to C8 group or a C4 to C10group. Therefore, each organic group may independently comprise a C1,C2, C3, C4, C5, C6, C7, C8 or a C10 group. An organic group may comprisean alkyl or an aryl. An organic group may comprise on or more linear,branched or cyclical alkyl. In some embodiments, an organic groupcomprises an aryl group. An alkyl or an aryl group may be substitutedwith one or more functional groups, such as a halogen, alcohol, amine orbenzene.

For example, the organic group may comprise a halogenated methane,ethane, propane, 2-methylpropane, 2,2-dimethylpropane (neopentane),n-butane, 2-methylbutane, 2,2-dimethylbutane, n-pentane,2-methylpantane, 3-methylpentane or an n-hexane. In some embodiments,the reactant comprises two halogen atoms. In some further embodiments,the at least two halogen atoms of the reactant may be attached todifferent carbon atoms. The halogen atoms may be the same halogen, forexample bromine, iodine, fluorine or chlorine. Alternatively, thehalogens may be different halogens, such as iodine and bromine, bromineand chlorine, chlorine and iodine. In some embodiments, the reactantcomprises 1,2-dihaloalkane or 1,2-dihaloalkene or 1,2-dihaloalkyne or1,2-dihaloarene, where the halogens are attached to adjacent carbonatoms.

In some embodiments, a reactant has a general formula R_(a)MX_(b) orR_(c)X_(d)M-MR_(c)X_(d). In the formula, a is 0, 1, 2 or 3, b is 4-a, cis 0, 1 or 2, d is 3-c, R is an organic group as described above, M isSi, Ge or Sn, and each X is independently any ligand. R may be ahydrocarbon. If a is two or three, or c is two, each R is selectedindependently. In some embodiments, each R is selected from alkyls andaryls. In some embodiments, R is an organic group as described above. Insome embodiments, R is alkyl or an aryl. For clarity, X may representdifferent ligands in one reactant species. Thus, in some embodiments, areactant may be, for example SiH₂Br₂, SiH₂I₂ or SiH₂Cl₂.

In some embodiments, a reactant has a more specific formulaR_(a)SiX_(b). More specifically, a reactant may have a formula R₃SiX,R₂SiX₂, RSiX₃, or SiX₄. However, in some embodiments, a silicon atomdoes not comprise four identical substituents. In some embodiments, thereactant is not SiH₄. In some embodiments, the reactant is not SiH₂Me₂.In some embodiments, a reactant is not SiH₂Et₂. In some embodiments,reactant is not Si₂H₂.

In some embodiments, a reactant has a more specific formulaR_(a)GeX_(b). More specifically, a reactant may have a formula R₃GeX,R₂GeX₂, RGeX₃, or GeX₄. However, in some embodiments, a Ge atom does notcomprise four identical substituents. In some embodiments, the reactantis not GeH₄.

In some embodiments, a reactant has a more specific formulaR_(a)SnX_(b). More specifically, a reactant may have a formula R₃SnX,R₂SnX₂, RSnX₃, or SnX₄. However, in some embodiments, a tin atom doesnot comprise four identical substituents. In some embodiments, thereactant is not SnH₄.

In some embodiments, X is hydrogen, a substituted or an unsubstitutedalkyl or aryl or a halogen. In some embodiments, X is H. In someembodiments, X is an alkyl or an aryl. In some embodiments, X is a C1 toC4 alkyl. In some embodiments, X is a substituted alkyl or aryl. In someembodiments, X is a substituted alkyl or aryl, wherein the substituentis same as M. In some embodiments, X is selected from a group consistingof H, Me, Et, nPr, iPr, nBu, tBu, M′Me₃, M′Et₃, M′Pr₃, M′Bu₃, Cl, Br, orI, wherein M′ is same as M. Thus, in such embodiments, for reactants offormula R_(a)SiX_(b), M′ is Si, for reactants of formula R_(a)GeX_(b),M′ is Ge, and for reactants of formula R_(a)SnX_(b), M′ is Sn.

In some embodiments, transition metal is deposited on a substrate as alayer. In such embodiments, transition metal forms a transition metallayer. As used herein, a “transition metal layer” can be a materiallayer that contains transition metal. As used herein, the term “layer”and/or “film” can refer to any continuous or non-continuous structureand material, such as material deposited by the methods disclosedherein. For example, layer and/or film can include two-dimensionalmaterials, three-dimensional materials, nanoparticles or even partial orfull molecular layers or partial or full atomic layers or clusters ofatoms and/or molecules. A film or layer may comprise material or a layerwith pinholes, which may be at least partially continuous. A seed layermay be a non-continuous layer serving to increase the rate of nucleationof another material. However, the seed layer may also be substantiallyor completely continuous.

Without limiting the current disclosure to any specific theory, in someembodiments it may be possible to produce transition metal layers withlow resistivity. The resistivity of a transition metal layer accordingto the current disclosure may be from about 5 μΩcm to about 300 μΩcm orfrom about 5 μΩcm to about 100 μΩcm, or from about 5 μΩcm to about 50μΩcm such as about 10 μΩcm, 15 μΩcm, 20 μΩcm or 30 μΩcm. In otherembodiments, the resistivity of a transition metal layer may be about 50μΩcm, 100 μΩcm, 150 μΩcm or 200 μΩcm.

The transition metal may be at least partly in elemental form. Thus, theoxidation state of transition metal may be zero. A transition metallayer can include additional elements, such as nitrogen, carbon and/oroxygen. Other additional or alternative elements are possible. In someembodiments, the transition metal layer may comprise significantproportions of other elements than transition metal. However, in someembodiments, transition metal layer may contain substantially onlytransition metal. Thus, transition metal layer may comprise, consistessentially of, or consist of transition metal. In some embodiments, thetransition metal layer may be a seed layer. A seed layer may be used toenhance the deposition of another layer.

In some embodiments, a transition metal layer may comprise, for example,about 60 to about 99 atomic percentage (at. %) transition metal, orabout 75 to about 99 at. % transition metal, or about 75 to about 95 at.% transition metal, or about 75 to about 89 at. % transition metal. Atransition metal layer deposited by a method according to the currentdisclosure may comprise, for example about 80 at. %, about 83 at. %,about 85 at. %, about 87 at. %, about 90 at. %, about 95 at. %, about 97at. % or about 99 at. % transition metal. In some embodiments, atransition metal layer may consist essentially of, or consist oftransition metal. In some embodiments, transition metal layer mayconsist essentially of, or consist of transition metal. Layer consistingof transition metal may include an acceptable amount of impurities, suchas oxygen, carbon, chlorine or other halogen, and/or hydrogen that mayoriginate from one or more precursors used to deposit the transitionmetal layer.

In some embodiments, the transition metal layer may comprise less thanabout 30 at. %, less than about 20 at. %, less than about 10 at. %, lessthan about 8 at. %, less than about 7 at. %, less than about 5 at. %, orless than about 2 at. % oxygen. In some embodiments, the transitionmetal layer may comprise less than about 20 at. %, less than about 15at. %, less than about 10 at. %, less than about 8 at. %, less thanabout 6 at. %, less than about 5 at. %, less than 4.5 at. %, or lessthan about 3 at. % carbon.

The substrate may be any underlying material or materials that can beused to form, or upon which, a structure, a device, a circuit, or alayer can be formed. A substrate can include a bulk material, such assilicon (e.g., single-crystal silicon), other Group IV materials, suchas germanium, or other semiconductor materials, such as a Group II-VI orGroup III-V semiconductor materials, and can include one or more layersoverlying or underlying the bulk material. Further, the substrate caninclude various features, such as recesses, protrusions, and the likeformed within or on at least a portion of a layer of the substrate. Forexample, a substrate can include bulk semiconductor material and aninsulating or dielectric material layer overlying at least a portion ofthe bulk semiconductor material. Substrate may include nitrides, forexample TiN, oxides, insulating materials, dielectric materials,conductive materials, metals, such as such as tungsten, ruthenium,molybdenum, cobalt, aluminum or copper, or metallic materials,crystalline materials, epitaxial, heteroepitaxial, and/or single crystalmaterials. In some embodiments of the current disclosure, the substratecomprises silicon. The substrate may comprise other materials, asdescribed above, in addition to silicon. The other materials may formlayers.

The method of depositing transition metal according to the currentdisclosure comprises providing a substrate in a reaction chamber. Inother words, a substrate is brought into space where the depositionconditions can be controlled. The reaction chamber may be part of acluster tool in which different processes are performed to form anintegrated circuit. In some embodiments, the reaction chamber may be aflow-type reactor, such as a cross-flow reactor. In some embodiments,the reaction chamber may be a showerhead reactor. In some embodiments,the reaction chamber may be a space-divided reactor. In someembodiments, the reaction chamber may be single wafer ALD reactor. Insome embodiments, the reaction chamber may be a high-volumemanufacturing single wafer ALD reactor. In some embodiments, thereaction chamber may be a batch reactor for manufacturing multiplesubstrates simultaneously.

In the method according to the current disclosure, the transition metalprecursor may be in vapor phase when it is in a reaction chamber. Thetransition metal precursor may be partially gaseous or liquid, or evensolid at some points in time prior to being provided in the reactionchamber. In other words, a transition metal precursor may be solid,liquid or gaseous, for example, in a precursor vessel or otherreceptacle before delivery in a reaction chamber. Various means ofbringing the precursor in to gas phase can be applied when delivery intothe reaction chamber is performed. Such means may include, for example,heaters, vaporizers, gas flow or applying lowered pressure, or anycombination thereof. Thus, the method according to the currentdisclosure may comprise heating the transition metal precursor prior toproviding it to the reaction chamber. In some embodiments, transitionmetal precursor is heated to at least 60° C., to at least 100° C., or toat least 110° C., or to at least 120° C. or to at least 130° C. or to atleast 140° C. in the vessel. In some embodiments, the transition metalprecursor is heated to at most 160° C., or to at most 140° C., or to atmost 120°, or to at most 100° C., or to at most 80° C., or to at most60° C. Also the injector system may be heated to improve the vapor phasedelivery of the transition metal precursor to the reaction chamber.

In this disclosure, “gas” can include material that is a gas at normaltemperature and pressure (NTP), a vaporized solid and/or a vaporizedliquid, and can be constituted by a single gas or a mixture of gases,depending on the context. Transition metal precursor may be provided tothe reaction chamber in gas phase. The term “inert gas” can refer to agas that does not take part in a chemical reaction and/or does notbecome a part of a layer to an appreciable extent. Exemplary inert gasesinclude He and Ar and any combination thereof. In some cases, molecularnitrogen and/or hydrogen can be an inert gas. A gas other than a processgas, i.e., a gas introduced without passing through a precursor injectorsystem, other gas distribution device, or the like, can be used for,e.g., sealing the reaction space, and can include a seal gas.

In the method according to the current disclosure, the reactant may becontacted with the substrate comprising a chemisorbed transition metalprecursor. The conversion of a transition metal precursor to transitionmetal may take place at the substrate surface. In some embodiments, theconversion may take place at least partially in the gas phase.

In the current disclosure, the deposition process may comprise acyclical deposition process, such as an atomic layer deposition (ALD)process or a cyclical chemical vapor deposition (VCD) process. The term“cyclical deposition process” can refer to the sequential introductionof precursor(s) and/or reactant(s) into a reaction chamber to depositmaterial, such as transition metal, on a substrate. Cyclic depositionincludes processing techniques such as atomic layer deposition (ALD),cyclical chemical vapor deposition (cyclical CVD), and hybrid cyclicaldeposition processes that include an ALD component and a cyclical CVDcomponent. The process may comprise a purge step between providingprecursors or between providing a precursor and a reactant in thereaction chamber.

The process may comprise one or more cyclical phases. For example,pulsing of transition metal and reactant may be repeated. In someembodiments, the process comprises or one or more acyclical phases. Insome embodiments, the deposition process comprises the continuous flowof at least one precursor. In some embodiments, a reactant may becontinuously provided in the reaction chamber. In such an embodiment,the process comprises a continuous flow of a reactant.

The term “atomic layer deposition” (ALD) can refer to a vapor depositionprocess in which deposition cycles, such as a plurality of consecutivedeposition cycles, are conducted in a reaction chamber. The term atomiclayer deposition, as used herein, is also meant to include processesdesignated by related terms, such as chemical vapor atomic layerdeposition, when performed with alternating pulses ofprecursor(s)/reactant(s), and optional purge gas(es). Generally, for ALDprocesses, during each cycle, a precursor is introduced to a reactionchamber and is chemisorbed to a deposition surface (e.g., a substratesurface that may include a previously deposited material from a previousALD cycle or other material), forming about a monolayer or sub-monolayerof material that does not readily react with additional precursor (i.e.,a self-limiting reaction). Thereafter, in some cases, a reactant (e.g.,another precursor or a reaction gas) may subsequently be introduced intothe process chamber for use in converting the chemisorbed precursor tothe desired material on the deposition surface. The reactant can becapable of further reaction with the precursor. Purging steps may beutilized during one or more cycles, e.g., during each step of eachcycle, to remove any excess precursor from the process chamber and/orremove any excess reactant and/or reaction byproducts from the reactionchamber.

CVD type processes typically involve gas phase reactions between two ormore reactants. The precursor(s) and reactant(s) can be providedsimultaneously to the reaction space or substrate, or in partially orcompletely separated pulses. The substrate and/or reaction space can beheated to promote the reaction between the gaseous reactants. In someembodiments the precursor(s) and reactant(s) are provided until a layerhaving a desired thickness is deposited. In some embodiments, cyclicalCVD processes can be used with multiple cycles to deposit a thin filmhaving a desired thickness. In cyclical CVD processes, the reactants maybe provided to the reaction chamber in pulses that do not overlap, orthat partially or completely overlap.

In some embodiments, transition metal precursor, reactant or both areprovided to the reaction chamber in pulses. In some embodiments, thetransition metal precursor is supplied in pulses, reactant supplied inpulses and the reaction chamber is purged between consecutive pulses oftransition metal precursor and reactant. A duration of providingreactant or transition metal precursor into the reaction chamber (i.e.reactant or transition metal precursor pulse time, respectively) may be,for example, from about 0.01 s to about 60 s, for example from about0.01 s to about 5 s, or from about 1 s to about 20 s, or from about 0.5s to about 10 s, or from about 5 s to about 15 s, or from about 10 s toabout 30 s, or from about 10 s to about 60 s, or from about 20 s toabout 60 s. The duration of a transition metal precursor or a reactantpulse may be, for example 0.03 s, 0.1 s, 0.5 s, 1 s, 1.5 s, 2 s, 2.5 s,3 s, 4 s, 5 s, 8 s, 10 s, 12 s, 15 s, 25 s, 30 s, 40 s, 50 s or 60 s. Insome embodiments, transition metal precursor pulse time may be at least5 seconds, or at least 10 seconds, or at least 20 seconds, or at least30 seconds. In some embodiments, transition metal precursor pulse timemay be at most 5 seconds, or at most 10 seconds or at most 20 seconds,or at most 30 seconds. In some embodiments, reactant pulse time may beat least 15 seconds, or at least 30 seconds, or at least 45 seconds, orat least 60 seconds. In some embodiments, reactant pulse time may be atmost 15 seconds, or at most 30 seconds or at most 45 seconds, or at most60 seconds.

The pulse times for transition metal precursor and reactant varyindependently according to process in question. The selection of anappropriate pulse time may depend on the substrate topology. For higheraspect ratio structures, longer pulse times may be needed to obtainsufficient surface saturation in different areas of a high aspect ratiostructure. Also the selected transition metal precursor and reactantchemistries may influence suitable pulsing times. For processoptimization purposes, shorter pulse times might be preferred as long asappropriate layer properties can be achieved. In some embodiments,transition metal precursor pulse time is longer than reactant pulsetime. In some embodiments, reactant pulse time is longer than transitionmetal precursor pulse time. In some embodiments, transition metalprecursor pulse time is same as reactant pulse time.

In some embodiments, providing a reactant or a transition metalprecursor to the reaction chamber comprises pulsing the reactant ortransition metal precursor over a substrate. In certain embodiments,pulse times in the range of several minutes may be used for transitionmetal precursor and/or reactant. In some embodiments, transition metalprecursor may be pulsed more than one time, for example two, three orfour times, before a reactant is pulsed to the reaction chamber.Similarly, there may be more than one pulse, such as two, three or fourpulses, of a reactant before transition metal precursor is pulsed (i.e.provided) to the reaction chamber.

A flow rate of the transition metal precursor or the reactant (i.e.transition metal precursor or reactant flow rate, respectively) may varyfrom about 5 sccm to about 20 slm. During providing a transition metalprecursor or a reactant to the reaction chamber, a flow rate of thetransition metal precursor or reactant may be less than 3,000 sccm, orless than 2,000 sccm, or less than 1,000 sccm, or less than 500 sccm, orless than 100 sccm. A transition metal precursor or reactant flow ratemay be, for example, form 500 sccm 1200 sccm, such as 600 sccm, 800 sccmor 1000 sccm. In some embodiments, a flow rate of the transition metalprecursor or the reactant to the reaction chamber is between 50 sccm and3,000 sccm, or between 50 sccm and 2,000 sccm, or between 50 sccm and1,000 sccm. In some embodiments, a flow rate of the transition metalprecursor or the reactant to the reaction chamber is between 50 sccm and900 sccm, or between 50 sccm and 800 sccm or between 50 sccm and 500sccm. In some embodiments, higher flow rates may be utilized. Forexample, a transition metal precursor or a reactant flow rate may be 5slm or higher. In some embodiments, a transition metal precursor orreactant flow rate may be 10 slm, 12 slm or 15 slm or 20 slm.

In some embodiments, the method comprises removing excess transitionmetal precursor from the reaction chamber by an inert gas prior toproviding the reactant in the reaction chamber. In some embodiments, thereaction chamber is purged between providing a transition metalprecursor in a reaction chamber and providing a reactant in the reactionchamber. In some embodiments, there is a purge step between every pulse.Thus, the reaction chamber may be purged also between two pulses of thesame chemistry, such as a transition metal precursor or a reactant.

As used herein, the term “purge” may refer to a procedure in which vaporphase precursors and/or vapor phase byproducts are removed from thesubstrate surface for example by evacuating the reaction chamber with avacuum pump and/or by replacing the gas inside a reaction chamber withan inert or substantially inert gas such as argon or nitrogen. Purgingmay be effected between two pulses of gases which react with each other.However, purging may be effected between two pulses of gases that do notreact with each other. For example, a purge, or purging may be providedbetween pulses of two precursors or between a precursor and a reactant.Purging may avoid or at least reduce gas-phase interactions between thetwo gases reacting with each other. It shall be understood that a purgecan be effected either in time or in space, or both. For example in thecase of temporal purges, a purge step can be used e.g. in the temporalsequence of providing a first precursor to a reactor chamber, providinga purge gas to the reactor chamber, and providing a second precursor tothe reactor chamber, wherein the substrate on which a layer is depositeddoes not move. For example in the case of spatial purges, a purge stepcan take the following form: moving a substrate from a first location towhich a first precursor is continually supplied, through a purge gascurtain, to a second location to which a second precursor is continuallysupplied. Purging times may be, for example, from about 0.01 seconds toabout 20 seconds, from about 0.05 s to about 20 s, or from about 1 s toabout 20 s, or from about 0.5 s to about 10 s, or between about 1 s andabout 7 seconds, such as 5 s, 6 s or 8 s. However, other purge times canbe utilized if necessary, such as where highly conformal step coverageover extremely high aspect ratio structures or other structures withcomplex surface morphology is needed, or in specific reactor types, suchas a batch reactor, may be used.

In some embodiments, the method according to the current disclosurecomprises a thermal deposition process. In thermal deposition, thechemical reactions are promoted by increased temperature relevant toambient temperature. Generally, temperature increase provides the energyneeded for the formation of transition metal in the absence of otherexternal energy sources, such as plasma, radicals, or other forms ofradiation. In some embodiments, the method according to the currentdisclosure is a plasma-enhanced deposition method, for example PEALD orPECVD.

In some embodiments, transition metal may be deposited at a temperaturefrom about 20° C. to about 800° C. For example, transition metal may bedeposited at a temperature from about 20° C. to about 450° C., or at atemperature from about 50° C. to about 450° C., or at a temperature fromabout 150° C. to about 450° C., or at a temperature from about 450° C.to about 800° C. In some embodiments of the current disclosure,transition metal may be deposited at a temperature from about 20° C. toabout 300° C., or at a temperature from about 300° C. to about 600° C.In some embodiments, transition metal may be deposited at a temperaturefrom about 50° C. to about 150° C., or at a temperature from about 250°C. to about 400° C., or at a temperature from about 500° C. to about700° C. For example, transition metal may be deposited at a temperatureof about 75° C. or about 125° C. or about 175° C., or about 225° C., orabout 200° C., or about 325° C. or about 375° C., or about 550° C., orabout 650° C., or about 750° C.

A pressure in a reaction chamber may be selected independently fordifferent process steps. In some embodiments, a first pressure may beused during transition metal precursor pulse, and a second pressure maybe used during reactant pulse. A third or a further pressure may be usedduring purging or other process steps. In some embodiments, a pressurewithin the reaction chamber during the deposition process is less than760 Torr, or wherein a pressure within the reaction chamber during thedeposition process is between 0.1 Torr and 760 Torr, or between 1 Torrand 100 Torr, or between 1 Torr and 10 Torr. In some embodiments, apressure within the reaction chamber during the deposition process isless than about 0.001 Torr, less than 0.01 Torr, less than 0.1 Torr,less than 1 Torr, less than 10 Torr, less than 50 Torr, less than 100Torr or less than 300 Torr. In some embodiments, a pressure within thereaction chamber during at least a part of the method according to thecurrent disclosure is less than about 0.001 Torr, less than 0.01 Torr,less than 0.1 Torr, less than 1 Torr, less than 10 Torr or less than 50Torr, less than 100 Torr or less than 300 Torr. For example, in someembodiments, a first pressure may be about 0.1 Torr, about 0.5 Torr,about 1 Torr, about 5 Torr, about 10 Torr, about 20 Torr or about 50Torr. In some embodiments, a second pressure is about 0.1 Torr, about0.5 Torr, about 1 Torr, about 5 Torr, about 10 Torr, about 20 Torr orabout 50 Torr.

The disclosure is further explained by the following exemplaryembodiments depicted in the drawings. The illustrations presented hereinare not meant to be actual views of any particular material, structure,or device, but are merely schematic representations to describeembodiments of the current disclosure. It will be appreciated thatelements in the figures are illustrated for simplicity and clarity andhave not necessarily been drawn to scale. For example, the dimensions ofsome of the elements in the figures may be exaggerated relative to otherelements to help improve the understanding of illustrated embodiments ofthe present disclosure. The structures and devices depicted in thedrawings may contain additional elements and details, which may beomitted for clarity.

FIGS. 1A and 1B illustrate an exemplary embodiment of a method 100according to the current disclosure. Method 100 may be used to form alayer comprising transition metal, i.e. a transition metal layer. Thetransition metal layer can be used during a formation of a structure ora device, such as a structure or a device described herein. However,unless otherwise noted, methods are not limited to such applications.

During step 102, a substrate is provided into a reaction chamber of areactor. The reaction chamber can form part of an atomic layerdeposition (ALD) reactor. The reactor may be a single wafer reactor.Alternatively, the reactor may be a batch reactor. Various phases ofmethod 100 can be performed within a single reaction chamber or they canbe performed in multiple reactor chambers, such as reaction chambers ofa cluster tool. In some embodiments, the method 100 is performed in asingle reaction chamber of a cluster tool, but other, preceding orsubsequent, manufacturing steps of the structure or device are performedin additional reaction chambers of the same cluster tool. Optionally, areactor including the reaction chamber can be provided with a heater toactivate the reactions by elevating the temperature of one or more ofthe substrate and/or the reactants and/or precursors.

During step 102, the substrate can be brought to a desired temperatureand pressure for providing transition metal precursor in the reactionchamber 104 and/or for providing reactant in the reaction chamber 106. Atemperature (e.g. of a substrate or a substrate support) within areaction chamber can be, for example, from about 50° C. to about 350°C., from about 150° C. to about 400° C., from about 200° C. to about350° C. or from about 500° C. to about 750° C. As a further example, atemperature within a reaction chamber can be from about 275° C. to about325° C., or from about 450° C. to about 600° C. Exemplary temperatureswithin the reaction chamber may be 100° C., 250° C., 300° C., 550° C.,650° C. or 700° C.

A pressure within the reaction chamber can be less than 760 Torr, forexample 400 Torr, 100 Torr, 50 Torr or 20 Torr, 5 Torr, Torr or 0.1Torr. Different pressure may be used for different process steps.

Transition metal precursor is provided in the reaction chambercontaining the substrate 104. Without limiting the current disclosure toany specific theory, transition metal precursor may chemisorb on thesubstrate during providing transition metal precursor in the reactionchamber. The duration of providing transition metal precursor in thereaction chamber (transition metal precursor pulse time) may be, forexample, 0.01 s, 0.5 s, 1 s, 1.5 s, 2 s, 4 s, 10 s, 20 s, 35 s, 50 s or60 s. In some embodiments, the duration of providing transition metalprecursor in the reaction chamber (transition metal precursor pulsetime) is may be longer than 5 s or longer than 10 s or longer than 30 s.Alternatively, transition metal purge time may be shorter than 60 s,shorter than 30 s, shorter than 10 s, shorter than 4 s, shorter than 1s., or shorter than 0.5 s.

When reactant is provided in the reaction chamber 106, it may react withthe chemisorbed transition metal precursor, or its derivate species, toform transition metal. The duration of providing reactant in thereaction chamber (reactant pulse time) may be, for example 0.01 s, 0.2s, 0.5 s, 1 s, 3 s, 4 s, 5 s, 7 s, 10 s, 11 s, 15 s, 25 s, 30 s, 45 s or60 s. In some embodiments, the duration of providing reactant in thereaction chamber is be shorter than 60 s, shorter than 40 s, shorterthan 20 s, shorter than 10 s, shorter than 4 s or about 3 s. Conversely,in some embodiments, a minimum duration for the reactant pulse may bedefined. For example, the reactant pulse time may be shorter than 60 s,shorter than 40 s, shorter than 25 s, shorter than 15 s, shorter than 8s, shorter than 5 s, or shorter than 2 s.

In some embodiments, transition metal precursor may be heated beforeproviding it into the reaction chamber. In some embodiments, reactantmay be heated before providing it to the reaction chamber. In someembodiments, the reactant may kept in ambient temperature beforeproviding it to the reaction chamber.

Stages 104 and 106, performed in any order, may form a deposition cycle,resulting in the deposition of transition metal. In some embodiments,the two stages of transition metal deposition, namely providing thetransition metal precursor and the reactant in the reaction chamber (104and 106), may be repeated (loop 108). Such embodiments contain severaldeposition cycles. The thickness of the deposited transition metal maybe regulating by adjusting the number of deposition cycles. Thedeposition cycle (loop 108) may be repeated until a desired transitionmetal thickness is achieved. For example about 50, 100, 200, 300, 400,500, 700, 800, 1,000, 1,200, 1,500 or 2,000 deposition cycles may beperformed.

The amount of transition metal deposited during one cycle (growth percycle) varies depending on the process conditions, and may be, forexample, from about 0.01 Å/cycle to about 6 Å/cycle, or from about 0.1Å/cycle to about 5 Å/cycle, 0.3 Å/cycle to about 4.5 Å/cycle, such asfrom about 0.5 Å/cycle to about 3.5 Å/cycle or from about 1.2 Å/cycle toabout 3.0 Å/cycle. For example, the growth rate may be about 1.0Å/cycle, 1.2 Å/cycle, 1.4. Å/cycle, 1.6 Å/cycle, 1.8 Å/cycle, 2 Å/cycle,2.2 Å/cycle, 2.4 Å/cycle. In some embodiments, growth rate of thetransition metal layer may be lower, such as from about 0.01 Å/cycle toabout 2 Å/cycle, or from about 0.1 Å/cycle to about 2 Å/cycle, whereasin some other embodiments, the growth rate may be higher, for examplefrom about 0.5 Å/cycle to about 2 Å/cycle, from about 1 Å/cycle to about2.5 Å/cycle, or from about 2 Å/cycle to about 6 Å/cycle, Depending onthe deposition conditions, deposition cycle numbers etc., transitionmetal layers of variable thickness may be deposited. For example,transition metal or transition metal-containing layer may have athickness between approximately 0.2 nm and 60 nm, or between about 1 nmand 50 nm, or between about 0.5 nm and 25 nm, or between about 1 nm and50 nm, or between about 10 nm and 60 nm. A transition metal layer mayhave a thickness of, for example, approximately 0.2 nm, 0.3 nm, 0.5 nm,1 nm, 1.5 nm, 2 nm, 2.5 nm, 3 nm, 3.5 nm, 4 nm, 4.5 nm, 5 nm, 6 nm, 8nm, 10 nm, 15 nm, 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 50 nm, 70 nm, 85 nmor 100 nm. The desired thickness may be selected according to theapplication in question.

Transition metal precursor and reactant may be provided in the reactionchamber in separate steps (104 and 106). FIG. 1B illustrates anembodiment according to the current disclosure, where steps 104 and 106are separate by purge steps 105 and 107. In such embodiments, adeposition cycle comprises one or more purge steps 103, 105. Duringpurge steps, precursor and/or reactant can be temporally separated fromeach other by inert gases, such as argon (Ar), nitrogen (N₂) or helium(He) and/or a vacuum pressure. The separation of transition metalprecursor and reactant may alternatively be spatial.

Purging the reaction chamber 103, 105 may prevent or mitigate gas-phasereactions between a transition metal precursor and a reactant, andenable possible self-saturating surface reactions. Surplus chemicals andreaction byproducts, if any, may be removed from the substrate surface,such as by purging the reaction chamber or by moving the substrate,before the substrate is contacted with the next reactive chemical. Insome embodiments, however, the substrate may be moved to separatelycontact a transition metal precursor and a reactant. Because in someembodiments, the reactions may self-saturate, strict temperature controlof the substrates and precise dosage control of the precursors may notbe required. However, the substrate temperature is preferably such thatan incident gas species does not condense into monolayers ormultimonolayers nor thermally decompose on the surface.

When performing the method 100, transition metal is deposited onto thesubstrate. The deposition process may be a cyclical deposition process,and may include cyclical CVD, ALD, or a hybrid cyclical CVD/ALD process.For example, in some embodiments, the growth rate of a particular ALDprocess may be low compared with a CVD process. One approach to increasethe growth rate may be that of operating at a higher depositiontemperature than that typically employed in an ALD process, resulting insome portion of a chemical vapor deposition process, but still takingadvantage of the sequential introduction of a transition metal precursorand a reactant. Such a process may be referred to as cyclical CVD. Insome embodiments, a cyclical CVD process may comprise the introductionof two or more precursors into the reaction chamber, wherein there maybe a time period of overlap between the two or more precursors in thereaction chamber resulting in both an ALD component of the depositionand a CVD component of the deposition. This is referred to as a hybridprocess. In accordance with further examples, a cyclical depositionprocess may comprise the continuous flow of one reactant or precursorand the periodic pulsing of the other chemical component into thereaction chamber. The temperature and/or pressure within a reactionchamber during step 104 can be the same or similar to any of thepressures and temperatures noted above in connection with step 102.

In some embodiments, the transition metal precursor is brought intocontact with a substrate surface 104, excess transition metal precursoris partially or substantially completely removed by an inert gas orvacuum 105, and reactant is brought into contact with the substratesurface comprising transition metal precursor. Transition metalprecursor may be brought in to contact with the substrate surface in oneor more pulses 104. In other words, pulsing of the transition metalprecursor 104 may be repeated. The transition metal precursor on thesubstrate surface may react with the reactant to form transition metalon the substrate surface. Also pulsing of the reactant 106 may berepeated. In some embodiments, reactant may be provided in the reactionchamber first 106. Thereafter, the reaction chamber may be purged 105and transition metal precursor provided in the reaction chamber in oneor more pulses 104.

In some embodiments, transition metal layer according to the currentdisclosure may have a resistivity of from about 5 μΩcm to about 300μΩcm. For example, the resistivity of a transition metal layer accordingto the current disclosure may be 10 μΩcm, 15 μΩcm, 20 μΩcm, 50 μΩcm, 100μΩcm, 150 μΩcm or 200 μΩcm. The thickness of a layer with saidresistivity may be, for example, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm or 60nm.

In some embodiments, the thickness non-uniformity of the depositedtransition metal layer is less than about 3%.

Resistivity of a transition metal layer may be reduced by using apost-deposition anneal. Annealing may be performed directly afterdeposition a transition metal layer, i.e. without additional layersbeing deposited. Alternatively, annealing may be performed afteradditional layers have been deposited. A transition metal layer may becapped before annealing. A capping layer may comprise, consistessentially of, or consist of silicon nitride. An annealing temperaturefrom about 320° C. to about 500° C. could be used. For example, anannealing temperature may be 330° C., 350° C., 380° C., 400° C., 430° C.or 450° C. or 470° C. Annealing may be performed in a gas atmospherecomprising, consist essentially of, or consist of argon, argon-hydrogenmixture, hydrogen, nitrogen or nitrogen-hydrogen mixture. Duration ofannealing may be from about 1 minute to about 60 minutes, for example 5minutes, 20 minutes, 30 minutes or 45 minutes. An annealing may beperformed at a pressure of 0.05 to 760 Torr. For example, a pressureduring annealing may be about 1 Torr, about 10 Torr, about 100 Torr orabout 500 Torr.

In a non-limiting example, a transition metal, such as a molybdenum,layer may be deposited at a pressure of at least 5 Torr, such as at apressure of about 6 Torr, 7 Torr or 8 Torr. Using a pressure between 5Torr and 10 Torr may lead to an advantageous growth rate of thetransition metal. In some embodiments, the growth rate of the transitionmetal may be, for example about 2 Å/cycle or about 3 Å/cycle. A pressurebetween 5 Torr and 10 Torr may decrease the thickness non-uniformity ofthe deposited material by, for example from about 60% to 90% relative tolow-pressure deposition (i.e to deposition pressure below 3 Torr).Further, the incubation time before the initiation of transition metallayer growth may be reduced. In the exemplary embodiment, the transitionmetal precursor is Mo(EtBz)₂ and the reactant comprises a dihaloalkane,such as a diiodoethane.

FIG. 2 illustrates an exemplary structure, or a portion of a device 200in accordance with the disclosure. Portion of a device or structure 200includes a substrate 202, a transition metal layer 204, and an optionalunderlayer 206 in between (e.g., in contact with one or both) substrate202 and transition metal layer 204. Substrate 202 can be or include anyof the substrate material described herein, such as a dielectric orinsulating layer. By way of example, dielectric or insulating layer canbe high-k material, such as, for example, a metallic oxide. In someembodiments, the high-k material has a dielectric constant higher thanthe dielectric constant of silicon oxide. Exemplary high-k materialsinclude one or more of hafnium oxide (HfO₂), tantalum oxide (Ta₂O₅),zirconium oxide (ZrO₂), titanium oxide (TiO₂), hafnium silicate(HfSiOx), aluminum oxide (Al₂O₃), lanthanum oxide (La₂O₃), titaniumnitride, and mixtures/laminates comprising one or more such layers.Alternatively, substrate material may comprise metal.

Transition metal layer 204 can be formed according to a method describedherein. In embodiments in which an underlayer 206, is formed, theunderlayer 206 may be formed using a cyclical deposition process. Insome embodiments, transition metal layer 204 can comprise predominantly,such as at least 50 at. %, at least 70 at. %, at least 90 at. % or atleast 95 at. %, elemental transition metal. In some embodiments, atransition metal layer may be deposited directly on the substrate. Insuch embodiments, there is no underlayer. As a further alternative, thestructure or a device according to the current disclosure may comprisemore than one layer between substrate and transition metal layer.

FIG. 3 illustrates a deposition assembly 300 according to the currentdisclosure in a schematic manner. Deposition assembly 300 can be used toperform a method as described herein and/or to form a structure or adevice, or a portion thereof as described herein.

In the illustrated example, deposition assembly 300 includes one or morereaction chambers 302, a precursor injector system 301, a transitionmetal precursor vessel 304, reactant vessel 306, a purge gas source 308,an exhaust source 310, and a controller 312.

Reaction chamber 302 can include any suitable reaction chamber, such asan ALD or CVD reaction chamber.

The transition metal precursor vessel 304 can include a vessel and oneor more transition metal precursors as described herein—alone or mixedwith one or more carrier (e.g., inert) gases. Reactant vessel 306 caninclude a vessel and one or more reactants as described herein—alone ormixed with one or more carrier gases. Purge gas source 308 can includeone or more inert gases as described herein. Although illustrated withthree source vessels 304-308, deposition assembly 300 can include anysuitable number of source vessels. Source vessels 304-308 can be coupledto reaction chamber 302 via lines 314-318, which can each include flowcontrollers, valves, heaters, and the like. In some embodiments, thetransition metal precursor in the precursor vessel may be heated. Insome embodiments, the vessel is heated so that the transition metalprecursor reaches a temperature between about 30° C. and about 160° C.,such as between about 100° C. and about 145° C., for example 85° C.,100° C., 110° C., 120° C., 130° C. or 140° C.

Exhaust source 310 can include one or more vacuum pumps.

Controller 312 includes electronic circuitry and software to selectivelyoperate valves, manifolds, heaters, pumps and other components includedin the deposition assembly 300. Such circuitry and components operate tointroduce precursors, reactants and purge gases from the respectivesources 304-308. Controller 312 can control timing of gas pulsesequences, temperature of the substrate and/or reaction chamber 302,pressure within the reaction chamber 302, and various other operationsto provide proper operation of the deposition assembly 300. Controller312 can include control software to electrically or pneumaticallycontrol valves to control flow of precursors, reactants and purge gasesinto and out of the reaction chamber 302. Controller 312 can includemodules such as a software or hardware component, which performs certaintasks. A module may be configured to reside on the addressable storagemedium of the control system and be configured to execute one or moreprocesses.

Other configurations of deposition assembly 300 are possible, includingdifferent numbers and kinds of precursor and reactant sources and purgegas sources. Further, it will be appreciated that there are manyarrangements of valves, conduits, precursor sources, and purge gassources that may be used to accomplish the goal of selectively and incoordinated manner feeding gases into reaction chamber 302. Further, asa schematic representation of an deposition assembly, many componentshave been omitted for simplicity of illustration, and such componentsmay include, for example, various valves, manifolds, purifiers, heaters,containers, vents, and/or bypasses.

During operation of deposition assembly 300, substrates, such assemiconductor wafers (not illustrated), are transferred from, e.g., asubstrate handling system to reaction chamber 302. Once substrate(s) aretransferred to reaction chamber 302, one or more gases from gas sources304-308, such as precursors, reactants, carrier gases, and/or purgegases, are introduced into reaction chamber 302.

FIG. 4 illustrates a line 406 and a via 404 in a semiconductor device400. The device is positioned on a semiconductor substrate 402. Thesubstrate 402 may contain any of the substrate material described in thecurrent disclosure. Additional functional layers (not depicted in thefigure) may be present on the substrate 402. A via 404 is in contactwith the substrate and a line 406. The via 404 may comprise, consistessentially of, or consist of transition metal deposited according tothe current disclosure. The line 406 may comprise consist essentiallyof, or consist of transition metal deposited according to the currentdisclosure, or it may comprise, consist essentially of, or consist ofanother metal such as copper. The via 404 and the line 406 aresurrounded by low k material.

FIG. 5 , panels A to D, exemplifies transition metal deposited accordingto the current disclosure in different contact applications. In allpanels, substrate is indicated with the numeral 502, source with numeral504, drain with numeral 506, gate with numeral 508 and a contact withnumeral 512. In panel A, transition metal deposited according to thecurrent disclosure is used in a source contact 510 and a drain contact514. In panel B, transition metal deposited according to the currentdisclosure is used in a gate contact 510, and in panel C, in a localinterconnect 510 between a gate 508 and a source 504. In panel D,transition metal is used in a connect 510 between a via and a contact512. In all the described examples, the structure in which transitionmetal according to the current disclosure is used, may comprise, consistessentially of, or consist of said transition metal.

FIG. 6 depicts buried power rail 602 comprising transition metaldeposited according to the current disclosure, and a FinFET structure604.

FIG. 7 illustrates a gate 702, in which a work function layer 704comprises, consist essentially of, or consist of transition metaldeposited according to the current disclosure in a similar device asdepicted in FIG. 5 .

FIG. 8 is an illustration of a 3D NAND 800 in which wordline 804comprises, consist essentially of, or consist of transition metaldeposited according to the current disclosure. The figure displaysexemplary embodiments of a channel 806, tunnel oxide 808, a charge traplayer 810 and a blocking oxide 812 for reference.

FIG. 9 illustrates an exemplary embodiment of a DRAM 900 with buriedwordline 906. In the figure, 902 indicates source, 904 gate and 910 abitline. Buried wordline 906 comprises, consist essentially of, orconsist of transition metal deposited according to the currentdisclosure.

The example embodiments of the disclosure described above do not limitthe scope of the invention, since these embodiments are merely examplesof the embodiments of the invention, which is defined by the appendedclaims and their legal equivalents. Any equivalent embodiments areintended to be within the scope of this invention. Various modificationsof the disclosure, in addition to those shown and described herein, suchas alternative useful combinations of the elements described, may becomeapparent to those skilled in the art from the description. Suchmodifications and embodiments are also intended to fall within the scopeof the appended claims.

The invention claimed is:
 1. A method of depositing a transition metalfrom any of groups 4 to 6 on a substrate by a cyclical depositionprocess, the method comprising: providing a substrate in a reactionchamber; providing a transition metal precursor to the reaction chamberin a vapor phase; and providing a reactant to the reaction chamber in avapor phase to form transition metal on the substrate; wherein thetransition metal precursor comprises a transition metal from any ofgroups 4 to 6, the reactant comprises a group 14 element selected fromGe or Sn, and at least 60% of transition metal is deposited as elementalmetal.
 2. The method according to claim 1, wherein the transition metalprecursor comprises a group 6 transition metal.
 3. The method accordingto claim 2, wherein the group 6 transition metal is molybdenum ortungsten.
 4. The method according to claim 2, wherein the group 6transition metal is molybdenum.
 5. The method according to claim 1,wherein the transition metal precursor comprises a metal-organicprecursor.
 6. The method according to claim 5, wherein the transitionmetal precursor comprises an additional ligand.
 7. The method accordingto claim 6, wherein the additional ligand is a halide.
 8. The methodaccording to claim 5, wherein the transition metal precursor comprises abenzene or a cyclopentadienyl group.
 9. The method according to claim 1,wherein the reactant comprises an organic group.
 10. The methodaccording to claim 1, wherein the reactant has a general formulaR_(a)MX_(b) or R_(c)X_(d)M-MR_(c)X_(d), wherein a is 0-3, b is 4-a, c is0, 1 or 2, d is 3-c, R is hydrocarbon, M is Ge or Sn, and each X isindependently any ligand.
 11. The method according to claim 10, whereinR is an alkyl or an aryl.
 12. The method according to claim 10, whereinX is hydrogen, a substituted or an unsubstituted alkyl a substituted oran unsubstituted aryl, or a halogen.
 13. The method according to claim12, wherein X is a substituted alkyl or the substituted aryl, andwherein the substituent is same as M.
 14. The method according to claim1, wherein the transition metal precursor is supplied in pulses,reactant supplied in pulses and the reaction chamber is purged betweenconsecutive pulses of transition metal precursor and reactant.
 15. Themethod according to claim 1, wherein the pressure in the reactionchamber is between 0.1 and 100 Torr.
 16. The method according to claim1, wherein the cyclical deposition process comprises a thermaldeposition process.
 17. The method according to claim 1, wherein thesubstrate comprises a dielectric surface and transition metal isdeposited on the dielectric surface.
 18. The method according to claim1, wherein transition metal is a group 4 or a group 5 metal.